Potentials of Cassava Peels as a Soil Amendment: II. Field Evaluation

Abstract

AbstractThe effect of cassava (Manihot esculenta Crantz) peels (CP), applied in different proportions with poultry droppings (PD) (chicken, Gallus gallus domesticus), on the growth of a root crop variously named cocoyam, taro, dasheen, and eddo [Colocasia esculenta (L.) Schott] was evaluated in the field over a 4‐yr period, which included 1 yr of fallow. The treatments 100% CP‐0% PD; 75% CP‐25% PD; 50% CP‐50% PD; 25% CP‐75% PD; and 0% CP‐100% PD were each applied at the rates of 0, 10, 25, and 50 Mg ha−1. At 10 Mg ha−1 the CP‐PD mixtures increased yield by 559, 328, and 311%, respectively, for the 1979, 1980, and 1982 croppings, thus emphasizing the value of the amendment. Significant increases in yield (P < 0.01) were obtained each year for each increment in rate. The mean yields (Mg ha−1) of 2.20, 5.09, and 2.40, respectively, for 1979, 1980, and 1982 demonstrate the residual benefit from these wastes after their incorporation into the soil. After 2 yr, treatment had no sustained effect on residual soil N. Residual (extractable) soil P increased from 11 mg kg−1 with 100% CP to 89 mg kg−1 with 75% CP‐25% PD, thus showing the relatively low and high potentials, respectively, of CP and PD for increasing soil P. Since the availability of PD is considerably less than CP, a 75% CP‐25% PD mixture at 25 Mg ha−1 was deemed appropriate for most efficient utilization of the wastes. At 10 Mg ha−1 of CP, total yield over 3 yr was also increased by 139%. With treatments containing PD, the corresponding yield increases were in the range 275 to 568%. Thus, while CP was a good soil amendment, there was need to incorporate PD with it to maximize yield.